This invention relates generally to heat exchangers, including exhaust gas coolers for use in vehicles and to a method of making heat exchangers.
In the vehicle industry, particularly the truck building industry, it is known to provide an EGR apparatus which re-circulates exhaust gas from a vehicle engine to reduce the generation of nitrogen oxides. The apparatus includes an EGR cooler which can cool the exhaust gas for re-circulation in order to drop the temperature of and reduce the volume of the exhaust gas which in turn lowers the combustion temperature in the engine without substantial decrease of output thereof. The effective result of such an apparatus is to reduce the generation of nitrogen oxides.
Published U.S. application No. 2006/0231243 describes an EGR cooler comprising a core made of parallel tubes which are separated from one another. A cylindrical shell surrounds the core and has plates at its opposite ends which are respectively affixed so as to close the ends of the shell. Bowl-shaped hoods are fixed to their respective plates so as to enclose the outer faces of the plates, these hoods respectively forming a central exhaust gas inlet and a central exhaust gas outlet. Mounting flanges appear to be connected to the outer ends of these hoods. Unlike the heat exchanger described herein, this known EGR cooler does not employ a cast housing forming the exterior of the cooler or heat exchanger.
A cast housing can be advantageous in certain heat exchanger applications as it can facilitate connections such as the use of connecting flanges and such housings can be manufactured at a reasonable cost, even when the volume of production is relatively low. The casting forming the exterior of the heat exchanger can in an exemplary embodiment be made of relatively low cost grey cast iron. Also the present invention enables the heat exchanger core to be mounted within a chamber of the casting by means of flanges fixedly attached to opposite ends of the core.